Refrigerant Cooled Coaxial Fuel Rail

Abstract

An engine fuel cooling system for vehicles exchanges heat between fuel and a flow of cold liquid in a coaxial fuel rail. The coaxial fuel rails include an inner fuel path through an inner tube surrounded by an outer cold liquid path through an outer tube, to cool the fuel provided to fuel injectors. The inner tube has no substantial direct contact with the outer tube to prevent external heat from being conducted to the inner tube. In one embodiment, the inner tube is solely supported by an fuel inlet fitting and injector hats teaching through the outer tube and into the inner tube. The coaxial fuel rail may be constructed using dip soldering.

I claim: 
     
         1 . A fuel cooling system for a vehicle including an internal combustion engine and an air conditioning system, said fuel cooling system comprising:
 a coaxial fuel rail including an outer tube and an inner tube inside the outer tube and spaced apart from the outer tube;   a fuel inlet fitting passing through the outer tube and into the inner tube providing fluid communication between a fuel source and the inner tube;   injector hats passing from the inner tube and through the outer tube providing fluid communication between the inner tube and fuel injectors; and   the coaxial fuel rail in thermal communication with the air conditioning system, the coaxial fuel rail configured to receive a cold liquid flow produced by an air conditioning system into a space between the inner tube and the outer tube, and a fuel flow from the fuel source through the fuel inlet fitting and into the inner tube, wherein heat is conducted from the fuel flow through walls of the inner tube into the cold liquid flow.   
     
     
         2 . The fuel cooling system of  claim 1 , wherein the inner tube has no direct contact with the outer tube. 
     
     
         3 . The fuel cooling system of  claim 2 , wherein the inner tube is held in position inside the outer tube by the fuel inlet fitting and the injector hats. 
     
     
         4 . The fuel cooling system of  claim 3 , wherein the fuel inlet fitting and the injector hats are attached to the inner tube and the outer tube by dip soldering. 
     
     
         5 . The fuel cooling system of  claim 3 , further including a sensor bung passing through the outer tube and into the inner tube, wherein the inner tube is solely held in position inside the outer tube by the fuel inlet fitting, the sensor bung, and the injector hats. 
     
     
         6 . The fuel cooling system of  claim 1 , wherein the cold liquid flow passes through both the coaxial fuel rail and an intake air heat exchanger. 
     
     
         7 . The fuel cooling system of  claim 6 , wherein the cold liquid flow passes first through the coaxial fuel rail, and then through the intake air heat exchanger, before returning to the compressor. 
     
     
         8 . The fuel cooling system of  claim 6 , wherein the cold liquid flow passes first through the intake air heat exchanger and then through the coaxial fuel, and refrigerant rail, before returning to the compressor. 
     
     
         9 . The fuel cooling system of  claim 7 , wherein the cold liquid flow is a refrigerant flow from an expansion valve the air conditioning system and flowing from the coaxial fuel rail to a compressor of the air conditioning system. 
     
     
         10 . The fuel cooling system of  claim 7 , wherein:
 the cold liquid flow is a cold coolant flow;   the cold coolant flow is cooled in a heat exchanger by a cold refrigerant flow; and   the heat exchanger receives the cold refrigerant flow from an expansion valve of the air conditioning system and returns the cold refrigerant flow to a compressor of the air conditioning system   
     
     
         11 . A fuel cooling system for a vehicle including an internal combustion engine and an air conditioning system, said fuel cooling system comprising:
 a coaxial fuel rail including an outer tube and an inner tube inside the outer tube and spaced apart from the outer tube having no direct contact with the outer tube;   a fuel inlet fitting passing through the outer tube and into the inner tube providing fluid communication between a fuel source and the inner tube;   injector hats passing from the inner tube and through the outer tube providing fluid communication between the inner tube and fuel injectors;   a sensor bung passing from the inner tube and through the outer tube, wherein:
 the inner tube is held in position inside the outer tube by the fuel inlet fitting, the sensor bung, and the injector hats; and 
 the fuel rails are constructed by dip soldering the outer tube, inner tube, fuel inlet fitting, the sensor bung, and the injector hats; and 
   the coaxial fuel rail configured to receive a cold refrigerant flow produced by an air conditioning system expansion valve into a space between the inner tube and the outer tube and a fuel flow from the fuel source through the fuel inlet fitting and into the inner tube, wherein heat is conducted from the fuel flow through walls of the inner tube into the cold refrigerant flow.   
     
     
         12 . A fuel cooling system for a vehicle including an internal combustion engine and an air conditioning system, said fuel cooling system comprising:
 a coaxial fuel rail including an outer tube and an inner tube inside the outer tube and spaced apart from the outer tube having no direct contact with the outer tube;   a fuel inlet fitting passing through the outer tube and into the inner tube providing fluid communication between a fuel source and the inner tube;   injector hats passing from the inner tube and through the outer tube providing fluid communication between the inner tube and fuel injectors;   a sensor bung passing from the inner tube and through the outer tube, wherein:
 the inner tube is held in position inside the outer tube by the fuel inlet fitting, the sensor bung, and the injector hats; and 
 the fuel rails are constructed by dip soldering the outer tube, inner tube, fuel inlet fitting, the sensor bung, and the injector hats; and 
   the coaxial fuel rail is configured to receive a cold coolant flow through a space between the inner tube and the outer tube and a fuel flow from the fuel source through the fuel inlet fitting and into the inner tube, wherein heat is conducted from the fuel flow through walls of the inner tube into the cold coolant flow, the cold coolant flow cooled in a heat exchanger by a cold refrigerant flow produced by an air conditioning system expansion valve of the air conditioning system.